But Uber now has big problems. It has become the poster child of "bro-culture" run amok. And late Tuesday night, Kalanick resigned, reportedly forced out of the company he founded amid claims of sexual harassment and a generally toxic work environment.

Here are five start-up founders that have been fired by their boards and investment teams.

Steve Jobs, Apple

The revered Silicon Valley icon was, famously, fired in 1985 from Apple, the company he and inventor Steve Wozniak co-founded in a garage. As Apple grew, they hired John Sculley to help run the company, and at first, things went well. But then "our visions of the future began to diverge" according to Jobs.

Apple's board of directors sided with Sculley. "So at 30, I was out. And very publicly out. What had been the focus of my entire adult life was gone, and it was devastating," Jobs said in his 2005 commencement address at Stanford.

"I didn't see it then, but it turned out that getting fired from Apple was the best thing that could have ever happened to me."-Steve Jobs, co-founder of Apple

Jobs didn't know what to do for a few months. "I felt that I had let the previous generation of entrepreneurs down — that I had dropped the baton as it was being passed to me. ... I was a very public failure, and I even thought about running away from the valley.

"But something slowly began to dawn on me," explained Jobs. "I still loved what I did. The turn of events at Apple had not changed that one bit. I had been rejected, but I was still in love. And so I decided to start over."

"I didn't see it then, but it turned out that getting fired from Apple was the best thing that could have ever happened to me. The heaviness of being successful was replaced by the lightness of being a beginner again, less sure about everything. It freed me to enter one of the most creative periods of my life," Jobs said.

"I'm pretty sure none of this would have happened if I hadn't been fired from Apple. It was awful tasting medicine, but I guess the patient needed it. Sometimes life hits you in the head with a brick."

"I let myself be in a weird position because it always felt like Ev's company. He funded it. He was the chairman. And I was this new guy who was a programmer, who had a good idea. I would not be strong in my convictions, basically, because he was the older, wiser one," says Dorsey in the same Vanity Fair feature.

It was a blow, he says. "It was like being punched in the stomach."

But Dorsey didn't let being fired slow him down. In 2009, he went on to found Square, a mobile payments platform, which, in the most recent financial quarter processed $13.6 billion in payments. In 2015, he was brought back on as the chief executive of Twitter to succeed then CEO Dick Costello. Twitter had stopped acquiring new users and the stock had been lagging for a year and a half. He's now running both Twitter and Square.

We are naming @adambain COO of Twitter, we're working to change the composition of our Board, and I will serve as CEO of Twitter and Square!

"I want people to wake up every day and the first thing they check is Twitter in order to see what's happening in the world," Dorsey says in a 2016 Vanity Fair feature. "It's a metaphor for checking the weather. Twitter has a similar potential."

Source: Zenefits

Parker Conrad of Zenefits.

Parker Conrad, Zenefits

Founded in 2013, after just two years, the cloud-based human resources service company Zenefits had raised hundreds of millions of dollars in venture capital funding at a valuation of $4 billion. But with its explosive growth came issues.

Additionally, the culture at the company had allegedly turned into a "Wolf of Wall Street"-esque free-for-all. A 2016 Wall Street Journal article revealed an email from Emily Agin, Zenefit's director of real estate and workplace services, that chastised, among other things, "Do not use the stairwells to smoke, drink, eat, or have sex."

Now, Conrad has started a new business, Rippling, which received $7 million in funding earlier this year, according to Crunchbase. The Zenefits experience taught Parker what to do differently. He appears to be taking a "more calculated approach after the mayhem of Zenefits," says TechCrunch.

"It's understanding the sort of complexities of growing a business and what's around the corner as you grow and the challenges that emerge," Conrad tells TechCrunch.

Andrew Mason, Groupon

"After four and a half intense and wonderful years as CEO of Groupon, I've decided that I'd like to spend more time with my family. Just kidding — I was fired today," Mason says in the note.

He took responsibility for poor financials and a crashing stock price, among other problems, saying, "As CEO, I am accountable. ... Groupon and you deserve the outside world to give you a second chance. I'm getting in the way of that. A fresh CEO earns you that chance."

"I'm OK with having failed at this part of the journey," says Mason. "I'll now take some time to decompress ... and then maybe I'll figure out how to channel this experience into something productive."

Jerry Yang, Yahoo

Jerry Yang and David Filo launched a directory for the internet from Stanford in 1994, "Jerry and David's guide to the World Wide Web." By 1995, they had changed the platform's name to "Yahoo!" The Internet search engine's stock surged in the dot-com bubble and plummeted in the bust. It tried, and failed, to develop a search technology to compete with Google and by 2008 was struggling, laying off large numbers of employees.

Yang has moved on. He sits on the board of Alibaba, which in 2014 raised $25 billion in the biggest IPO in U.S. history. He also now has his own venture capital firm, AME Cloud Ventures, of which Yang says in a 2014 Forbes article: "I feel like this is a place to look forward and not look back too much."